1. Field of the Invention
The present invention relates to an active matrix substrate in which a plurality of pixels are provided in a matrix configuration, and a display panel and a display device including the same.
2. Description of the Related Art
In recent years, accompanying the widespread use of thin displays represented by a liquid crystal display device, the applications thereof have been diversified still further. For example, the liquid crystal display device is sometimes used in a dashboard (an instrument panel) or the like of a car. In other words, in order to respond to the diversification of the applications of liquid crystal display devices, it has been desired to provide the liquid crystal display device with a display panel having an odd-shaped display region such as a trapezoidal display region, a circular display region or a polygonal display region with at least five vertexes other than an existing rectangular display region, so that there has been a demand for an increase in the degree of freedom of the design of the outer shape thereof. Furthermore, in the liquid crystal display device, it has also been desired from the viewpoint of cost and a mechanism to reduce the size of regions other than the display region so as to enhance an effective display area ratio in the display panel.
On the other hand, as described in JP 2000-75257 A or JP 2004-212500 A, for example, conventional liquid crystal display devices including a display region formed to have an odd shape such as an elliptical shape, a sectional shape or a polygonal shape have been proposed. More specifically, in these conventional examples, a rectangular liquid crystal display device is formed first and then broken or divided, whereby the liquid crystal display device including the odd-shaped display region is produced.
Also, in conventional liquid crystal display devices, as described in JP 2005-195788 A, it has been proposed, for example, to form a sectional cut-out portion in a circular liquid crystal panel and provide the cut-out portion and an outer peripheral portion with input terminals of two kinds of signal lines for active driving of the liquid crystal panel, respectively.
In other words, in this conventional example, a plurality of input terminals that are connected respectively to a plurality of scan lines arranged concentrically on an active matrix substrate and input scan signals have been provided along an edge of the above-described cut-out portion. Also, in this conventional example, a plurality of input terminals for data line that are connected respectively to a plurality of data lines provided individually to extend toward the center of the circle on the active matrix substrate and input data signals have been provided along an edge of the above-described outer peripheral portion. Then, in this conventional example, the plurality of scan lines and the plurality of data lines have been arranged to intersect each other on the active matrix substrate, and a plurality of pixels including a TFT (Thin Film Transistor), a pixel electrode, etc. have been provided at the intersections, thus making it possible to perform active driving pixel by pixel in the circular liquid crystal panel.
However, the conventional liquid crystal display devices as described above have had a problem in that brightness unevenness and a line defect, in which only the brightness of the pixels for one scan line or those for one data line is different from the brightness of the pixels for the other lines, are generated, resulting in a lowered display quality.
More specifically, in the above-described conventional liquid crystal display devices, when the odd-shaped display region as mentioned above is formed, the scan lines and the data lines that have different numbers of pixels have been formed in the plurality of scan lines and the plurality of data lines on the active matrix substrate. Therefore, in the conventional liquid crystal display devices, the scan lines and the data lines that have different loads have been formed in the plurality of scan lines and the plurality of data lines, so that it has not been possible to prevent the generation of the brightness unevenness and the line defect, resulting in a lowered display quality in some cases.
Further, in the conventional liquid crystal display devices, it is also conceivable to correct the non-uniformity of respective loads in the plurality of scan lines and the plurality of data lines by changing the magnitude (voltage value) of respective signals for the scan lines and the data lines depending on the number of pixels. However, in the case of active driving by changing the signal voltage value as described above, it is required to minutely change the respective signal voltage values for the scan lines and the data lines depending on the difference in the number of pixels or to change the signal voltage values for the respective data lines according to the brightness of information to be displayed. Therefore, it has been practically impossible to correct the load non-uniformity by changing the signal voltage values.